74 MEMOIRS ON THE COLEOPTERA 



becoming more elongate, the hind tarsi rather long, due to the not- 

 ably elongate second joint; the hind tibiae are rapidly broadened from 

 base to apex as a rule, with the tip oblique and armed with two long 

 and unequal terminal spurs in the male, and more slender, parallel, 

 truncate at tip and with moderate spurs in the female. The meta- 

 sternum between the coxae is broad and the mesosternum before it 

 reduced to a thick transverse bead, or at least much less developed 

 than it usually is in Stilbus. The antennae, palpi, general structure 

 of the head, the scutellum and other features, are almost exactly 

 as in Stilbus, except that the last palpal joint is less securiform. The 

 raised plaque behind the middle coxae is moderate in size and 

 angulate to rounded in form. The sculpture of the elytra is one of 

 the most constant and distinctive of the generic structural charac- 

 ters of Acylomus, and the genus can be recognized unfailingly by 

 simply viewing it under adequate power. The entire surface of the 

 elytra is always strigilato-reticulate and the punctures more or less 

 evenly serial internally and confused on the flanks- have always 

 the form of broad, transverse, superficial and lunulate scratches, 

 bearing each a minute decumbent hair; the posterior and partially 

 inclosed surface of each puncture is smooth and polished ; there is no 

 exception to this form of sculpture known to me and it is unique in 

 the family. 



In geographic range Acylomus is essentially southern and tropical, 

 and most of the Central American species assigned to Olibnis by 

 Dr. Sharp belong to it. In fact it is very doubtful if any true Olibrus, 

 in the sense of the European bicolor or the American pallipes, occurs 

 in southern Mexico or in Central America, it being a peculiarly 

 subarctic type in the family. The species of Acylomus are numerous 

 but more monotonous than those of any other genus, possibly 

 excepting Phalacrus; those in my collection may be known as follows : 



Species of the Florida and Cuban regions 2 



Species of the northern Atlantic regions, extending in northern latitudes 



through to the true Pacific fauna 7 



Species of the Texas and Mexican regions 9 



2 Prosternal process broad apically, with four stout setiform spines at tip. 

 Body rather large, oval, very convex, polished, the elytra opalescent, 

 dark rufo-piceous throughout above, the under surface ferruginous; 

 head half as wide as the prothorax, smooth though with distinct 

 punctulation; antennae rather long, slender, the slender club as long 

 as the funicle; prothorax very obsoletely micro-reticulate; strongly 



